1. Field of the Invention
The present invention relates to a dummy bit elimination device for eliminating dummy bits added to an,FEC (Forward Error Correction) code which is transmitted on a submarine cable system.
2. Description of the Prior Art
In a submarine cable system, a processing device for generating FEC code, for example a Reed-Solomon code, based on an optical signal input adds the dummy bits to the FEC code to simplify the configuration thereof.
Adding the dummy bit according to a conventional method, however, increases a bit rate on the communication channel. A transmission loss is increased in accordance with the increased bit rate. Thus, for example, it was required to compensate the loss by increasing a number of repeaters.
An object of the present invention is to provide a dummy bit elimination device for eliminating the dummy bit added to the FEC code that is transmitted on the submarine cable system.
According to a first aspect of the present invention, there is provided a dummy bit elimination device included in a coding apparatus, which device comprises: means for eliminating only dummy bits from FEC code supplied thereto so as to output only the FEC Code; wherein the coding apparatus comprises: a means for converting an optical signal into an electrical signal data; a demultiplexer for demultiplexing the data; a coding means for generating an FEC (Forward Error Correction) code having the demultiplexed data and additional parities, and dummy bits for each of the demultiplexed data; a multiplexer for multiplexing inputs thereto; and a means for converting an output of the multiplexer into an optical signal; and wherein the dummy bit elimination device and an output of the dummy bit elimination device are fed to the multiplexer.
According to a second aspect of the present invention, there is provided a coding apparatus, which apparatus comprises: a means for converting an optical signal into an electric signal data; a demultiplexer for demultiplexing the data; a coding means for generating an FEC code having the demultiplexed data and additional parities, and dummy bits for each of demultiplexed data; a dummy bit eliminating means for eliminating only the dummy bits from outputs of the coding means so as to output only the FEC codes; a multiplexer for multiplexing outputs of the dummy bit eliminating means; and a means for converting an output of the multiplexer into an optical signal.
The coding apparatus may be combined with a submarine cable system.
According to a third aspect of the present invention, there is provided a coding apparatus which comprises: a coding means for continuously outputting an FEC code word having an input data and additional parities, and dummy bits to simplify an FEC coding; and a dummy bit eliminating means for eliminating only the dummy bits from a continuity consisting of the FEC code and the dummy bits so as to output only the FEC code.